Mixer for particulate materials

ABSTRACT

A particulate material mixing machine has a horizontal mixing drum which is separable into two parts to gain access to its interior and to internal mixing and material-transfer paddles, the paddles being rotated by two separately supported and driven rotary drive shafts which respectively enter the two parts of the drum and which are aligned when the machine is ready for use, and the paddles being borne by drivingly-interconnected hubs which are designed to slide onto and off the shafts for ease of maintenance.

United States Patent Hohnfeld et al. Dec. 9, 1975 [5 MIXER FORPARTICULATE MATERIALS 1,017,820 2/1912 Svebilius 416/200 1,385,4847/1921 Case 220/4 D [75] Inventors- Peter 1,467,537 9/1923 Dornier416/200 Langenbel'g, Buer, both of Germany 2,010,579 8/1935 Broadfield259/105 3,526,467 9/1970 Kime 1 416/200 [73] Asslgnee' 23:2 SoehneOsnabrueck 3,652,062 3/1972 Baker 259/68 x Filedi 1973 PrimaryExaminerBilly J. Wilhite [21] AppL No; 410,248 Assistant Examiner-AlanCantor [30] Foreign Application Priority Data [57] CT Oct 28 1972Germany 2252996 A particulate material mlxing machine has a hor1zontalmixing drum which is separable into two parts to 52 US. Cl. 25 200 gainaccess its interim and mixing and E Int z material-transfer paddles, thepaddles bemg rotated by [58] Field of 64 105 two separately supportedand driven rotary drive S 220/4C f 8 6 shafts which respectively enterthe two parts of the drum and which are aligned when the machine is [56]References Cited ready for use, and the paddles being borne bydrivingly-interconnected hubs which are designed to UNITED STATESPATENTS slide onto and off the shafts for ease of maintenance. 444,4701/1891 Villavaso 1. 259/21 917,206 4/1909 Watts 416/200 8 Clams, 5Drawmg Flgllres U.S. Patent Dec. 9, 1975 Sheet1of4 3,924,835

US. Patent Dec. 9, 1975 shw 2 of4 3,924,835

US. Patent Dec. 9, 1975 Sheet4 0f4 3,924,835

MIXER FOR PARTICULATE MATERIALS The present invention relates to amixing machine for the continuous mixing and preparation of particulatematerials such as powders and granular or small-sized aggregateproducts.

In the past, frequent attempts have been made to developcontinuously-operating mixers, particularly for mixing syntheticmaterials. In addition to horizontal mixers of a type having horizontalmixing vessels containing mixing paddles which rotate about horizontalaxes, vertical mixers have been proposed. Vertical mixers havevertically disposed mixing vessels and vertical paddle-carrying shaftsrotating therein. Such mixers utilise the gravitational force to assistin moving the material being mixed through the mixers. It has beenproposed, furthermore, to arrange conventional high speed mixers oneafter the other in cascade fashion and to connect them together throughintermediate connecting ducts in such a fashion that the material beingmixed is compelled to move successively from mixer to I'I'IIXBI'.

Previous attempts have failed to provide a satisfactory mixer whichadequately meets the requirements of practice, in particular, in thefield of the preparation of synthetic materials. Only with extruders hasit been possible to operate continuously, to plasticise syntheticmaterial, granulate and feed the resulting essentially homogeneousplasticised synthetic material mass continuously to an extrusion head.An extruder which has a mixing tool in the form of a worm or screw-feedauger inside a mixing vessel, subjects the synthetic material beingprocessed to a relatively high pressure and is designed to produce aneffect quite different from the effect of mixing and preparation ofsynthetic materials required of high speed mixers. High speed mixers aredesigned to produce material which is fluid in the prepared form,generally granulate and not a homoge neously plasticised mass. In thiscontext, preparation takes place in a state substantially of nopressure, and the particles to be mixed and prepared are subjected tovigorous eddying motion which, whilst maintaining the fluidity, achievesthe desired mixing effect quickly and in a controllable manner.

The adaptation of the principles of known batchoperating high speedmixing to continuous mixing could not be achieved satisfactorily amongstother things because known mixing machines could not be adequatelycontrolled to produce the requisite uniformity of mixture. Furthermore,known machines could not be adapted economically to the very widelyvarying conditions which are encountered in the practice.

To this end the machine in accordance with the invention, commencingfrom the type introductorily described, is primarily characterised inthat the tool carrier shaft consists of two axially aligned, independentshaft sections, those of whose ends which are disposed away from oneanother and outside the mixing chamber are equipped with single-endedbearings, can be separately driven and are fitted with tool setsarranged on them in an exchangeable fashion. In order to be able toadjust the material flow conditions in a zonally differentiated fashionin the mixer chamber and in order to control the swell time there,preferentially each shaft section will be capable of speed variationand/or versible.

The mixer vessel can furthermore advantageously consist of at least twovessel section with radial separating places, a main separating planebeing disposed between adjoining vessel sections, in fact between theinternal ends of the shaft sections. A further embodiment of theinvention is characterised in that one of the two machine sectionslocated in one side of the main separating plane or joint plane, issupported in such a fashion as to be capable of opposite axialdisplacement relatively to the other, or, instead of this or in additionthereto, is supported in such a fashion as to be capable of pivotingabout a tilting axis disposed parallel to and an interval from thecommon axis of the shaft sections. This kind of design makes it possibleto achieve a rapid access to the shaft sections and to the tool setsarranged thereon, so that quick and easy cleaning, repair and resettingoperations can be carried out.

The tool sets will preferentially comprise a substan tially ring-shapedhub which can be slid on to the associated shaft section, which hub isprovided on its end face with drive pins and bores, so that in each caseadjacent shaft section mounted hubs can be coupled to one another, thehubs of the tool sets arranged in each case on a shaft section, in eachcase forming a casing or envelope surrounding the shaft. In thiscontext, the particular hub located nearest to the external end of ashaft section, can be in driving engagement with the shaft through theagency of a spring ring element, and thus form the initial element fromwhich the rotational drive is consecutively transmitted to the hubs ofthe tool sets. In order to ensure that the tool set hubs in each casearranged adjacent one another upon a shaft section, are firmly heldtogether, it is provided, in accordance with the invention that the hubin each case assigned to the internal end of a shaft section, embracesan end cap fitted over the shaft end, and is attached to the shaft endthrough a set of axial screws distributed around the shaft axis. Theaxial screws, which perform their securing function even if thedirections of rotation are opposite, constitute fixing elements by whichall the hubs arranged upon a shaft section are held together andmaintained in a mutual driving relationship. The shaft section here, asfar as all the intervening tool set hubs are concerned simply performs asupporting function so that the tool set, on the lease of the cap-likehub of the particular innermost tool set, can all be rapidly withdrawnfrom the shaft and re-assembled on it again in any arbitrary order orarrangement, and this also includes the possibility of mutual angularstagger in the circumferential sense.

At least some of the tool sets will have paddles or blades with acertain angle of incidence, not unlike a propeller, this in a mannerknown per se. The position of the tool paddles or blades within a toolset, will conveniently be the same throughout. In association with hubrings simply acting as spacers and tool sets whose blades do not exhibitany angle of incidence, it is possible within the machine to build uptool set groups which are optimally matched to the particular specialconditions governing synthetic materials which require mixing, in themixer chamber of the vessel flow conditions being developed, in a stateof continuous material transfer, which satisfy all requirements of theparticular case.

The invention will now be described by way of example with reference tothe accompanying drawings, in which:

FIG. 1 is a simplified side elevation of a mixing machine embodying theinvention;

FIG. 2 is a plan view of the machine shown in FIG. 1;

FIG. 3 is an end elevation of the machine shown in FIGS. 1 and 2;

FIG. 4 is an end elevation similar to FIG. 3, of part of the machinealong the line IVIV in FIG. 2, and

FIG. 5 is a longitudinal section through the mixer vessel on the line VVof FIG. 2.

The machine illustrated in the drawing has a cylindrical mixer vessel 1having a top inlet connection 2 at one end and a bottom dischargeconnection 3 at its other end. The vessel 1 has its central axis 4horizontal. In this instance, the mixer vessel 1 is composed of fourvessel sections, 5, 6, 7 and 8. The two central sections 6, 7 are joinedtogether about a central plane which is substantially normal to the axis4, i.e. the plane is radially disposed. The vessel end sections 5 and 8,which adjoin the sections 6, 7 about radial planes, 10, 11, constituteinput and discharge zones of the mixer chamber respectively. The two endsections 5, 8 are attached to bearing units 12 and 13, by flangeconnections. Conveniently the mixer vessel 1 has a double-wallconstruction, so that heating media or coolants can flow in a spacebetween the two walls. It is advantageous for each section 5, 6, 7 and 8to be a double-wall unit which is equipped with its own separate heatingagent or coolant connections (not shown). The vessel sections can thenbe supplied with heating media or coolant individually to enabledifferential control of the temperature of the internal walls of thevessel 1 along its length.

The machine incorporates a tool carrier consisting of two colinear shaftsections 14, whose common axis coincides with the axis 4. The two shaftsections 14, 15 are mounted in single-ended fashion in the bearing units12, 13 at their opposite ends which are located outside the mixerchamber. The inner portions of the shaft sections 14, 15 areconsequently cantilevered from the units 12, 13. The two shaft sections14, 15 are in each case driven independently of one another. To thisend, in the illustrated example, each shaft section is assigned aseparate drive motor 16, 17 whose speed and/or direction of rotation canbe changed. Output shaft of the motors 16, 17 carry pulleys 18, 19 anddrive belts 20, 21 pass around these pulleys and pulleys 22, 23 on theoutermost ends of the shaft sections 14, 15. Alternative drivetransmissions could be provided instead of belts and pulleys, ifpreferred.

The bearing unit 12 is permanently fixed upon a common machine frame 24.Bearing unit 13, however, is supported thereon by a mounting whichpermits of limited axial displacement as well as transverse tilting ofthe unit 13. The mounting includes a table 25 carrying the bearing unit13, and the table has a bearing bush 26 attached to its underside. Thebrush 26 can slide to and fro longitudinally on a bearing cylinder 27 inthe direction of the arrow 28. The bush 26, and with it the table 25 isable to pivot about the axis 29 of the bearing cylinder 27. The bearingaxis 29 is disposed parallel to but spaced from the central axis 4 ofthe mixer vessel and the shaft sections 14, 15, but coincides with theshaft axis of the drive motor 17 and the axis of the pulley 19. Thisdesign makes it possible to pivot or tilt the table and bearing unit 13without interrupting the drive connection between the motor 17 and theassociated shaft section 15. Axial displacement can be produced by apneumatic or hydraulic actuator, or by a spindle adjuster mechanism. Aspindle drive for axial adjustment has been indicated in FIG, 4 simplyby a handcrank 30. To swing the bearing unit 13 about the axis 29, aspindle drive mechanism 31 equipped with a handwheel 32 is shown. Thismechanism, too, can be replaced by alternative drive arrangements, suchas exemplified above in connection with the axial adjustment. To supportthe illustrated drive mechanism 31, which is articulated at 33 to thebearing unit 13, a mounting plate 34 on the machine frame 24 is used, asseen in FIG. 4.

Once the flange connection between the two central sections 6, 7 hasbeen released, the parts of the machine section located (in FIG. 1) tothe right of the central plane 9 can be displaced slightly to the rightin the direction of the arrow 28 and then swung out of the way so thatthe vessel interior is quickly and easily ac cessible. In theillustrated example, axial displacement simply serves to clear mutualcentring engagement between the vessel sections 6, 7 so that the ensuingpivoting motion can take place. It would be possible, however, simply todisplace the entire machine section disposed to one side of the centralplane 9 (in FIG. 1), axially along a suitably dimensioned slide wayrather than to tilt, as described above, in order to move apart theadjacent ends of the vessel sections 6, 7, apart for access to themachine interior.

Furthermore, it is feasible for both bearing units 12, 13 to be slidableand/or pivotable.

As the illustration of FIG. 5 shows in more detail, the innermost endsof the shaft sections l4, 15 are close to gether but are slightly spacedapart, terminating at either side of the main plane 9. A plurality oftool sets 35, 36, 37, 38 and 25, 36', 37', 38 and 39', which will bedescribed in more detail hereinafter, are carried by the two shaftsections l4, 15 respectively.

The tool set 35 located closest to the outer end of the shaft section14, has an annular hub 40 slipped over the shaft section 14 and issecured thereto in a rotational driving relationship by means of aspring ring element, details of which are omitted for clarity. Four toolblades or paddles 41 are fitted to the hub 40, the paddles being spacedapart at intervals around the hub periphery. The tool blades or paddles41, as illustrated, are skewed, relative to a radial plane through thehub 40 and have symmetrical triangular prismatic crosssections, in themanner of a propeller. Accordingly the paddles impart to incomingmaterial to be mixed a component of motion directed in the main transferdirection D when shaft section 14 is rotated. At or close to itsleft-hand end (in FIG. 5), the hub 40 has a set of four terminal toolblades 42 uniformly distributed about its periphery. The blades 42 havea symmetrical triangular prismatic cross-section and each has a flatside 43 disposed in a radial plane normal to the axis 4. As a result oftheir design, each of the tool blades 42, always exerts upon incomingmaterial a driving force in the main transfer direction D, irrespectiveof the particular direction of rotation of the shaft section 14. Ineffect the blades 42 constitute clearing elements which keep theterminal plate 44 of the mixing chamber 45 free of material being mixed.

The tool set 36 also has an annular hub 46 which is simply slipped on tothe shaft section 14 but is not in driving engagement therewith,however. Instead, the hub 46 is driven by the first hub 40. To this end,axial drive pins transmit drive from the neighbouring hub 40, to hub 46,the pins engaging in corresponding bores in the hub 40 and in the hub46. To effect this drive or coupling between the hubs, there are atleast two, but preferably three or more drive pins and correspondingpairs of bores, which are uniformly distributed circumferentially.Fundamentally, numerous drive pins and corresponding bores will bepreferred because this makes it possible to stagger the hubs and theirblades circumferentially in relation to one another. The larger thenumber of drive pins and bores, the finer is the incremental adjustmentwhich is possible in this stagger. The hub 46 carries a group of bladesor paddles 41 akin to the paddles on the first hub 40 and alsoskew-orien tated.

Proceeding inwardly of the tool set 36 is the adjoining tool set 37.This tool set comprises a hub 47 which once again carries four toolblades 48, the blades 48 being circumferentially staggered relative tothe blades of tool set 36. Like all the tool blades, blades 48 extendalmost to the internal wall of the vessel 1. The tool blades 48 herehave a skew, or angle of incidence corresponding to that of the toolblades 41. The tool set 38 which then follows, likewise has an annularhub 49 identical to hub 47 but carrying at its circumference a set oftool blades 50 which are oppositely skewed relative to the blades 41.Express reference is made to the drawing for the angles of incidence ofthe blades of the different groups thereof. For the rest, the toolblades 50 are identical in configuration to those 48. Again, between thehubs 47, 49 and 47, 46, there is the drive pin connection of the formalready described, this being shown in the cut-away illustration of FIG.5. Here, the drive pins 51 can clearly be seen. As FIG. 5 clearly shows,the other tool sets on the shaft section 14 proceeding inwardly in thedirection of the main plane 9, alternate in type between the designs ofthe tool sets 37 and 38. The innermost tool set 39 also possesses a hub52 and, united therewith and embracing the innermost end of the shaftsection 14, a cap or cover 53. By means of a set of axial screws (notshown) distributed around the shaft axis 4, the cap 53 is attached tothe internal end of the shaft section so that the tool set 39, with itshub and cap portion, secures all the assembled row of tool sets on thisshaft section. The circumference of the hub 52 carries blades 54 whichcorrespond to those 50 of the tool set 38.

The design of the tool sets on the shaft section is similar to thatemployed in respect of the shaft section 14, so that as far as theillustration of the parts in the drawing is concerned, no .furtherexplanation is required here. In principle, the tool sets on the shaftsection 15 are disposed in a mirror symmetrical arrangement, about themain plane 9, in relation to those on the shaft section 14. Oneexception here, however, is the tool set 39' whose blades 55 have a skewor angle of incidence which is identical to that of the blades 54 of thetool set 39. In this fashion, straight forward transfer of material fromthe vessel section 6, to the left of the main plane to the vesselsection 7 located at the right thereof, is ensured. As can be seen, thehubs of the tool sets arranged on the shaft sections 14, 15 togetherform a casing surrounding the shaft sections. The shaft sections simplyperform a supporting function and are not in rotary engagement with eachof the tool sets. This design is not only particularly simpleconstructionally and cheap to manufacture, but also makes possible rapidassembling, and dismantling of the tool sets. Once the end tool sets 39,39 have been released, the remaining sets can be drawn off axially andslipped back on again, without difficulty. With a similarly favourablefacility for the straightforward balancing of the components which areinvolved in rotational motion, it is thus possible, using simple means,to vary the particular arrangement and relationship of tool sets on theshaft section in an arbitrary fashion and thus take account ofconditions arising when mixing and preparing the most varied kinds ofbulk materials. By employing blade arrangements which partially producedisplacement in the transfer direction, other blade arrangements actingin opposition to the transfer direction or still further bladearrangements producing no net axial effect, and/or by changing the speedand/or direction of rotation of at least one shaft section, it ispossible to effect a zonal variation in the eddying action and in thetransfer speed or time of dwell of material being mixed in the machine,as may be required. Using spacers which simply constitute hub ringswithout blades and which are also coupled through axial drive pins, toneighbouring tool bearing hubs, the axial intervals between groups oftools can likewise be rapidly and simply adapted to meet the particularmixing requirements.

Although not illustrated in the drawings, the mixing vessel can beconstructed from several part-cylindrical sections, in accordance withGerman Patent application No. 17821 15, which corresponds to US. Pat.No. 3,722,831, which defines communicating mixing chamber sectionscombined to form an overall mixing chamber through a mechanism of mutualmaterial transfer, in which mixing chamber sections there is in eachcase a separate tool carrier shaft with tool sets. With this kind ofdesign, the two mixing chamber sections will conveniently be disposedhorizontally adjacent one another, the machine then not having onecylindrical mix ing vessel 1 but for example an overall vessel made upof two part-cylindrical vessels. Within each part vessel, thearrangement and embodiment of components described in FIG. 5, would thenbe retained.

Although the invention is illustrated and described with reference to aplurality of preferred embodiments thereof, it is to. be expresslyunderstood that it is in no way limited to the disclosure of such aplurality of preferred embodiments, but is capable of numerousmodifications within the scope of the appended claims.

We claim:

1. A machine for the continuous mixing of particulate materials,comprising:

a substantially horizontally-disposed cylindrical mixer vessel,

a material feed opening and a material discharge opening at oppositeends of said vessel,

a rotatable, horizontal tool carrier axially disposed within saidvessel, and

a plurality of mixer paddle tools for rotation in said vessel mounted onsaid tool carrier, said paddle tools including paddles which extendradially towards and terminate adjacent an inner wall of said vessel,

said tools being detachably mounted on said tool carrier, and said toolcarrier comprising two independent shafts disposed in line with one endof each shaft projecting outwardly from an associated end of saidvessel,

two bearing units each rotatably receiving the outwardly-projecting endsof a different one of the tool carrier shafts,

separate rotary drive means coupled to said tool carrier shafts,

said mixer vessel comprises at least two vessel sections which meet at aradial joint plane, adjacent inner ends of said tool shafts beingdisposed on either side of said joint plane,

portion of said machine is located to one side of said joint plane, andmeans for supporting said portion for axial shifting movement relativeto the remainder of said machine on the opposite side of said plane toallow access to the interior of sai'd'vessel and pivotal movementrelative to the remainder of said machine on the opposite side of saidplane to allow access to the interior of said vessel, the axis ofmovement of pivotal portion being disposed parallel to and spaced fromthe common axis of the aligned tool carrier shafts.

2. A machine according to claim 1, wherein said drive means are operableto control the rotation of their associated tool shafts independently ofeach other.

3. A machine according to claim 1, wherein said mixing vessel includesfour vessel sections, two middle sections thereof adjoining one anotherat said joint plane, and the remaining two vessel sections respectivelyclefining feed and discharge zones at the opposite ends bf -5' saidmixing vessel.

4. A machine according to claim 1, characterised in that at least someof said paddle tools have skewed pro- 8 peller-like paddle blades forimparting linear motion to material being mixed when said tool carrieris rotated.

5. A machine according to claim 1, wherein said paddle tools have paddleblades, said blades of the paddle tools mounted nearest to the outer endof each shaft each have a symmetrical triangular prismaticcross-section. one face thereof lying in a radial plane.

6. A machine according to claim 5, wherein at least a part of the paddleblades mounted on said shaft are oriented oppositely with respect toanother part of said paddle blades mounted on said shaft.

7. A machine according to claim 1, wherein said mixing vessel comprisesa plurality of part-cylindrical sections which define communicatingmixing chamber sections and are combined into an overall mixing chamberto produce mutual material transfer.

8. A machine according to claim 1, wherein said paddle tools are mountedon a plurality of separate contiguous hubs, each hub serving as adetachable mounting for a plurality of paddle tools, each hub havingpin-andhole drive coupling means confronting an adjacent hub todrivingly and detachably connect a pair of adjacent hubs, the hubmounted closest to the axial end of said vessel being drivinglyconnected to one of said carrier shafts, drive means and a cap mountedon the free end of each one of said shafts for retaining said pluralityof hubs thereon.

1. A machine for the continuous mixing of particulate materials,comprising: a substantially horizontally-disposed cylindrical mixervessel, a material feed opening and a material discharge opening atopposite ends of said vessel, a rotatable, horizontal tool carrieraxially disposed within said vessel, and a plurality of mixer paddletools for rotation in said vessel mounted on said tool carrier, saidpaddle tools including paddles which extend radially towards andterminate adjacent an inner wall of said vessel, said tools beingdetachably mounted on said tool carrier, and said tool carriercomprising two independent shafts disposed in line with one end of eachshaft projecting outwardly from an associated end of said vessel, twobearing units each rotatably receiving the outwardlyprojecting ends of adifferent one of the tool carrier shafts, separate rotary drive meanscoupled to said tool carrier shafts, said mixer vessel comprises atleast two vessel sections which meet at a radial joint plane, adjacentinner ends of said tool shafts being disposed on either side of saidjoint plane, a portion of said machine is located to one side of saidjoint plane, and means for supporting said portion for axial shiftingmovement relative to the remainder of said machine on the opposite sideof said plane to allow access to the interior of said vessel and pivotalmovement relative to the remainder of said machine on the opposite sideof said plane to allow access to the interior of said vessel, the axisof movement of pivotal portion being disposed parallel to and spacedfrom the common axis of the aligned tool carrier shafts.
 2. A machineaccording to claim 1, wherein said drive means are operable to controlthe rotation of their associated tool shafts independently of eachother.
 3. A machine according to claim 1, wherein said mixing vesselincludes four vessel sections, two middle sections thereof adjoining oneanother at said joint plane, and the remaining two vessel sectionsrespectively defining feed and discharge zones at the opposite ends ofsaid mixing vessel.
 4. A machine according to claim 1, characterised inthat at least some of said paddle tools have skewed propeller-likepaddle blades for imparting linear motion to material being mixed whensaid tool carrier is rotated.
 5. A machine according to claim 1, whereinsaid paddle tools have paddle blades, said blades of the paddle toolsmounted nearest to the outer end of each shaft each have a symmetricaltriangular prismatic cross-section, one face thereof lying in a radialplane.
 6. A machine according to claim 5, wherein at least a part of thepaddle blades mounted on said shaft are oriented oppositely with respectto another part of said paddle blades mounted on said shaft.
 7. Amachine according to claim 1, wherein said mixing vessel comprises aplurality of part-cylindrical sections which define communicating mixingchamber sections and are combined into an overall mixing chamber toproduce mutual material transfer.
 8. A machine according to claim 1,wherein said paddle tools are mounted on a plurality of separatecontiguous hubs, each hub serving as a detachable mounting for aplurality of paddle tools, each hub having pin-and-hole drive couplingmeans confronting an adjacent hub to drivingly and detachably connect apair of adjacent hubs, the hub mounted closest to the axial end of saidvessel being drivingly connected to one of said carrier shafts, drivemeans and a cap mounted on the free end of each one of said shafts forretaining said plurality of hubs thereon.